Is cigarette smoking associated with diabetic retinopathy?

The relationship between cigarette smoking and diabetic retinopathy is examined in this report. All participants were examined between September 1980 and July 1981 as part of a population-based study in southwestern Wisconsin. Exposure data on cigarette smoking at the time of examination were derived from a set of questions about present or past smoking history, duration of smoking, and number of cigarettes smoked per day. Retinopathy status was determined according to the modified Airlie House classification. The rate of diabetic retinopathy varied from 21% in those who had diabetes for 0-4.9 years to 97% in those who had diabetes for 15 or more years, for persons diagnosed before 30 years of age, and from 28% to 78% for comparable durations in those diagnosed at 30 years or older. There was no association between smoking history and duration of diabetes. In participants diagnosed before age 30, the relative risk for the presence of retinopathy in smokers compared with those who had never smoked was 1.06 (95% confidence limits (CL) 0.97-1.18); in participants diagnosed at 30 years or older it was 0.89 (95% CL 0.75-1.06). There was no relationship between the risk or severity of retinopathy and number of cigarettes smoked daily, or the number of pack-years smoked while diabetic. These data suggest that there is no excess risk of retinopathy in smokers or ex-smokers when contrasted with those who never smoked.